JP4609019B2 - Thermal flow sensor and manufacturing method thereof - Google Patents

Description

  The present invention relates to a thermal flow sensor.

  For example, Patent Document 1 discloses a thermal flow sensor that detects the flow rate of a fluid by taking advantage of the heat generated by the heater being taken away by the fluid passing near the heater.

  The thermal flow sensor disclosed in Patent Document 1 is configured such that a flow rate detection unit (sensor unit) including a heater (heating resistor) formed in a thin part is formed on a substrate (semiconductor substrate) having a thin part. A flow rate detection chip, a circuit chip that is electrically connected to the flow rate detection unit via a connection wire (connection body), and has a circuit unit that performs signal processing on the output of the flow rate detection unit, and a connection wire (connection body) It has a lead (connector) electrically connected to the circuit part and a support (blocking support lead) on which at least the flow rate detection chip is mounted.

  Then, with the flow rate detection chip mounted on the support, each connection between the connection wire, the flow rate detection unit, and the circuit unit so that a part of the flow rate detection unit including the heater is exposed to the fluid to be measured. The part, the connection part of the connection wire, the circuit part and the lead, and the range including the circuit chip are integrally covered with a molding material.

Further, the support body is bent in the vertical direction from the bottom surface portion on which the flow rate detection chip is arranged, and has one end surface and both side surfaces for positioning the flow rate detection chip. Positioned by the end face and the both side faces, it is arranged on the support so as to close the cavity portion (cavity) below the thin film portion of the substrate. Therefore, the hollow portion below the thin wall portion of the flow rate detection chip is blocked by the support and is not directly exposed to the fluid to be measured (air flow). Since fluctuations are reduced, noise in the output signal can be reduced.
Japanese Patent No. 3328547

  However, in the thermal flow sensor shown in Patent Document 1, the flow rate detection chip has a structure in which the hollow portion at the lower part of the thin portion is closed while being arranged on the support and is not directly exposed to the fluid to be measured. ing. Therefore, when the peripheral part of the cavity part is fixed (for example, bonded) to the support so as to surround the cavity part of the substrate, the temperature of the fluid (air) sealed in the cavity part is changed. Since it is difficult to follow the ambient temperature change, there is a problem that a measurement error occurs.

  In addition, if the flow rate detection chip is partially fixed to the support, the cavity portion can communicate with the outside via a gap between the flow rate detection chip and the support. . However, since there is a predetermined clearance (that is, a gap) between both side surfaces (and one end surface) of the support body for positioning the flow rate detection chip and the side surface of the flow rate detection chip facing, There is a risk that the mold material may enter the gap. Depending on the variation in the arrangement of the flow rate detection chip and the variation in the formation of both side surfaces (and one end surface) of the support, the mold material penetrates into the cavity part and the cavity part is blocked, resulting in a measurement error as described above. It is also possible that it will occur.

  In view of the above problems, an object of the present invention is to provide a thermal flow sensor that can reduce noise due to turbulent flow and can reduce measurement errors due to temperature changes, and a method for manufacturing the same.

In order to achieve the above object, the thermal flow sensor according to any one of claims 1 to 8 is a flow rate detection chip in which a flow rate detection unit including a heater formed in a thin part is formed on a substrate having a thin part. And a circuit chip having a circuit unit that is electrically connected to the flow rate detection unit via the first connection wire and controls input / output of the flow rate detection unit, and electrically connected to the circuit unit via the second connection wire And a support for mounting at least the flow rate detection chip, and a part of the flow rate detection unit including the heater is exposed to the fluid to be measured with the flow rate detection chip mounted on the support. As described above, each connection part between the first connection wire, the flow rate detection unit and the circuit part, each connection part between the second connection wire, the circuit part and the lead, and the range including the circuit chip are integrally covered with the molding material. It has been made.

First, as described in claim 1, the support body includes a groove portion in which the flow rate detection chip is disposed, a hollow portion in a lower portion of the thin portion of the substrate, and an external portion on the flow rate detection chip in a state in which the flow rate detection chip is disposed. In the state where the flow rate detection chip is disposed in the groove portion, the flow rate detection portion forming surface of the flow rate detection tip and the support surface are substantially flush with the groove side surface and the flow rate detection tip. The gap between the side faces is characterized in that at least a part of the gap is blocked by injecting an adhesive at least at a position to prevent the molding material from entering the gap during molding.

  As described above, according to the present invention, the flow rate detecting chip is positioned and arranged in the groove portion formed in the support body, and the cavity portion is not directly exposed to the fluid to be measured, and thus the support body is not disposed below the cavity portion. Compared with the configuration, noise due to turbulent flow can be reduced. In addition, the hollow portion at the lower part of the thin part of the substrate is not completely closed by the support, and is in communication with the outside on the flow rate detection chip by the communication part formed on the support. Accordingly, the temperature of the fluid in the cavity can change following the temperature change around the thermal flow sensor, so that measurement errors due to the temperature change can be reduced.

Further, in a state where the flow rate detection chip is disposed in the groove portion, the flow rate detection portion forming surface of the flow rate detection chip and the support surface are substantially the same plane, and in the gap between the groove portion side surface and the flow rate detection chip side surface, At least a part of the gap is closed by injecting an adhesive at least at a position where the mold material is prevented from entering the gap during molding. As a result, the cavity portion is not completely closed by the support, and the mold material penetrates to the cavity portion while being configured to communicate with the outside on the flow rate detection chip via the communication portion. Is blocked.

  Although the cavity portion is configured to be indirectly exposed to the outside (fluid to be measured) on the flow rate detection chip via the communication portion, if the communication portion is large, the object that has entered the cavity portion via the communication portion will be described. Care must be taken because turbulent flow may occur due to the measurement fluid and noise may increase. Moreover, only one place may be provided with respect to the cavity part, and multiple places may be provided. It may be determined together with the shape, size, etc. in consideration of the ease of turbulent flow in the cavity and the ability to follow changes in ambient temperature.

In addition, since the flow rate detection chip is disposed in the groove portion, positioning can be performed with high accuracy, and the adhesive can be easily injected into a predetermined position of the gap between the groove side surface and the flow rate detection chip side surface .

Furthermore , the flow rate detection chip can be more firmly fixed to the support by the adhesive.

The constituent material of the support is not particularly limited. For example, as described in claim 2 , if the lead is made of the same material, the configuration of the thermal flow sensor can be simplified.

According to a third aspect of the present invention, it is preferable that a communication groove portion communicating with a gap between the groove portion side surface and the flow rate detection chip side surface is formed in the support body as the communication portion. In this case, since the communication portion is constituted by the communication groove portion and the gap, the configuration of the communication portion can be simplified. In addition, since the fluid to be measured can enter the cavity portion from the outside on the flow rate detection chip via the gap, a large amount of fluid to be measured does not enter the cavity portion, and noise due to turbulence is reduced. be able to.

In addition, if the communication groove part communicates with the clearance gap between the groove part side surface which opposes at least one side surface of a flow volume detection chip like Claim 4 , the measurement error by a temperature change can be reduced. .

Further, as described in claim 5, it is preferable that the support has a structure in which an adhesive reservoir is formed in a part of the groove. In this case, even if the adhesive has a good fluidity (low viscosity) at the time of injection, the adhesive can be kept in the pool portion which is a predetermined position of the gap between the groove side surface and the flow rate detection chip side surface. .

The support may be configured by processing (etching or the like) one member, or may be configured by a plurality of members. For example, as described in claim 6 , the first support body having a through hole in which the flow rate detection chip can be arranged, and the second support body having a communication portion and mounting the first support body. May be. In this case, with the first support mounted on the second support, the through-hole formed in the first support and the surface of the second support (first support mounting surface) Thus, a groove portion can be formed.

At this time, as described in claim 7 , the second support body has a communication portion between the outer surface of the first support body and the side surface of the second support body facing the outer surface. It is preferable that a communication groove portion communicating with the gap is formed. In this case, since the communication portion is constituted by the communication groove portion and the gap, the configuration of the communication portion can be simplified. In addition, since the fluid to be measured can enter the cavity portion from the outside on the flow rate detection chip via the gap, a large amount of fluid to be measured does not enter the cavity portion, and noise due to turbulence is reduced. be able to.

The substrate in the invention according to claim 1-7, having as claimed in claim 8, by applying the semiconductor substrate as the substrate, easily thin portions by a general semiconductor manufacturing technology (etching) It can be.

Next, the invention of claim 9-1 1, relates to a method for producing a thermal flow sensor having the above-described structure.

According to a ninth aspect of the present invention, the support includes a groove portion in which the flow rate detection chip is disposed, and a hollow portion below the thin portion of the substrate and the outside on the flow rate detection chip in a state in which the flow rate detection chip is disposed. In the state where the flow rate detection chip is arranged in the groove portion so that the flow rate detection portion forming surface of the flow rate detection chip and the support surface are substantially flush with each other, the side surface of the groove portion and the side surface of the flow rate detection chip An adhesive is injected into the gap between the two, and at least a part of the gap is blocked so that the mold material does not enter the gap during integral molding with the mold material.

As described above, according to the present invention, by injecting and solidifying the adhesive into the gap between the groove side surface and the flow rate detection chip side surface, it is possible to prevent the molding material from entering the gap (hollow portion). Therefore, it is possible to form a thermal flow sensor that can reduce noise due to turbulent flow and reduce measurement errors due to temperature changes.

Effect of the invention according to claim 1 0 are the same as the operation and effect of the invention of claim 6, it will not be described.

As described in claim 1 1, after the flow rate detection chip is fixed in the through hole of the first support member, it is preferable to mount the first support on a second support. In this case, it is possible to prevent the communication portion from being blocked by the adhesive regardless of the configuration of the communication portion.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
1A and 1B are diagrams showing a schematic configuration of a thermal flow sensor in the present embodiment, where FIG. 1A is a plan view and FIG. 1B is a cross-sectional view taken along a line AA in FIG.

  As shown in FIGS. 1A and 1B, a thermal flow sensor 100 in the present embodiment is partially exposed to air as a fluid to be measured, and a flow rate detection chip 10 that detects the flow rate, A circuit chip 20 that controls input / output of the flow rate detection chip 10, a lead 30 that is electrically connected to the circuit chip 20 and connected to the outside, a support 40 on which at least the flow rate detection chip 10 is mounted, and a flow rate detection chip 10, a circuit chip 20, and a molding material 50 that integrally covers a part of the lead 30. 1A and 1B, reference numerals 60 and 61 denote bonding wires that electrically connect the flow rate detection chip 10 and the circuit chip 20, and the circuit chip 20 and the leads 30, respectively.

  The flow rate detection chip 10 is made of, for example, a silicon semiconductor substrate. The flow rate detector is formed in the thin part 12 and the thin part 12 made of a thin insulating film formed on the cavity part 11 by etching the semiconductor substrate to form the cavity part 11. And a heater 13. In this way, when a silicon semiconductor substrate is used as the substrate, the thin portion 12 can be easily formed by etching from the back side of the thin portion 12, and the heater 13 can detect the flow rate with high sensitivity as will be described later. It can function as a part. Therefore, the thermal flow sensor 100 has a small and highly sensitive flow rate detection chip 10 and can be manufactured at low cost.

  Here, the flow rate detection chip 10 will be described in more detail with reference to FIG. FIG. 2 is a plan view showing the configuration of the flow rate detection chip 10. In FIG. 2, the mold material 50 is omitted for the sake of convenience, and the right side of the two-dot chain line indicates a portion covered with the mold material 50.

  Since the thin portion 12 is formed to be very thin compared to the substrate, the heat capacity of the thin portion 12 is kept low, and the thin portion 12 ensures thermal insulation from the substrate. As shown in FIG. 2, the thin portion 12 is formed with a pair of heaters 13 made of heating resistors on the upstream side and the downstream side of the air flow. Further, a pair of temperature sensing parts 14 made of resistance temperature detectors are formed on the substrate around the thin part 12 on the upstream side and the downstream side of the air flow so as to sandwich the heater 13.

  The heater 13 has a function of sensing its own temperature based on a change in its own resistance temperature coefficient in addition to a function as a heating element that generates heat according to the amount of current supplied. Then, the flow rate of the air is detected based on the heat generated by the circulating air among the heat generated in the upstream and downstream heaters 13. Furthermore, the current supplied to each heater 13 based on the temperature difference between the upstream heater 13 and the upstream temperature sensing unit 14 and the temperature difference between the downstream heater 13 and the downstream temperature sensing unit 14. The amount is controlled.

  In FIG. 2, reference numeral 15 denotes a wiring part, and reference numeral 16 denotes a pad part as an electrode provided at an end of the wiring part 15. The flow rate detection unit and the circuit unit of the circuit chip 20 are electrically connected via the bonding wire 60 connected to the pad unit 16. As described above, the flow rate detection unit is configured by the heater unit 13, the temperature sensing unit 14, and the wiring unit 15 formed in the thin portion 12. As shown in FIG. 2, a part of the wiring portion 15 and the pad portion 16 are covered with a molding material 50 (a region on the right side of the two-dot chain line in FIG. 2).

  The support 40 is mounted with at least the flow rate detection chip 10 and is formed by processing (etching or the like) the same material as the lead 30 in the present embodiment. Thus, if it comprises with the same material as the lead | read | reed 30, the structure of the thermal type flow sensor 100 can be simplified. In addition, since the flow rate detection chip 10 is mounted on the support 40, the cavity 11 of the flow rate detection chip 10 is not directly exposed to the air that is the fluid to be measured. Noise due to turbulent flow can be reduced compared to a configuration that is not performed.

  Specifically, as shown in FIGS. 1A and 1B, a groove 41 having substantially the same dimensions as the outer shape of the flow rate detection chip 10 is formed on one end side of the support 40 by, for example, half-etching. The flow rate detection chip 10 is disposed in the groove portion 41 (fixed to the bottom surface of the groove portion with an adhesive, for example, with the back surface of the flow rate detection portion forming surface down). And in this arrangement | positioning state, it is comprised so that the flow volume detection part formation surface of the flow volume detection chip | tip 10 may become substantially the same plane as the surface of the support body 40. FIG. Therefore, the influence of the turbulent flow generated by the step between the flow rate detection chip 10 and the support 40 is reduced. Moreover, the generation | occurrence | production of the burr | flash is suppressed at the time of integral molding by the molding material 50 mentioned later. In the present embodiment, the circuit chip 20 having a circuit unit (not shown) for controlling the input / output of the flow rate detection unit on the other end side of the support 40 has the back surface of the circuit unit forming surface facing downward. For example, it is adhered and fixed to the support 40 with an adhesive.

  The support body 40 is formed with a communication portion that communicates the cavity portion 11 with the outside on the flow rate detection chip 10 in a state where the flow rate detection chip 10 is disposed in the groove portion 41. That is, the cavity 11 of the flow rate detection chip 10 is not completely closed by the support body 40 and is in a state of communicating with the outside (air that is the fluid to be measured) on the flow rate detection chip 10 through the communication part. Therefore, since the temperature of the fluid existing in the cavity 11 can change following the temperature change around the thermal flow sensor 10, the temperature of the fluid is higher than the structure in which the cavity 11 is sealed by the support 40. Measurement errors due to changes can be reduced.

  Specifically, as shown in FIGS. 1A and 1B, the groove portion 41 is formed with a predetermined clearance with respect to the flow rate detection chip 10, and the flow rate detection chip 10 is positioned and arranged in the groove portion 41. In this state, a predetermined gap 42 exists between the side surface of the groove portion 41 and the side surface of the flow rate detection chip 10 facing the groove portion 41. In the present embodiment, a communication groove 43 that communicates with the gap 42 is formed by half-etching in the lower part of the cavity 11, and the communication groove 43 and the gap 42 constitute a communication part. Thus, if a communicating part is comprised by the communicating groove part 43 and the clearance gap 42, the structure of a communicating part can be simplified. Further, since air as the fluid to be measured can enter the cavity 11 from the outside on the flow rate detection chip 10 through the gap 42, a large amount of air does not enter the cavity 11 and turbulent flow Can reduce noise.

  In addition, the communication part may be provided only at one place with respect to the hollow part 11 or may be provided at a plurality of places. It may be determined together with the shape, size, etc., taking into account the ease of turbulent flow in the cavity 11 and the ability to follow ambient temperature changes. In this embodiment, the communication groove part 43 is formed along the air flow direction, and two communication parts are formed with the flow rate detection chip 10 in between.

  Further, at least a part of the gap 42 is closed by injecting the filler 44 into a position of the gap 42 where at least the mold material 50 is prevented from entering during integral molding (described later) with the mold material 50. As a result, the cavity portion 11 of the flow rate detection chip 10 is not completely closed by the support body 40, and the mold material 50 is in a state of being in communication with the outside on the flow rate detection chip 10 through the communication portion. This prevents the molding material 50 from entering the cavity 11 during the integral molding, thereby blocking the cavity 11.

  The filler 44 can be injected into the gap 42 between the side surface of the groove portion 41 and the side surface of the flow rate detection chip 10, and can be cured after injection to suppress the mold material 50 from entering the gap 42. Any material can be applied. For example, a gel (silicon-based, fluorine-based, etc.), a thermoplastic resin, an adhesive, or the like can be applied. However, when the adhesive is applied, the flow rate detection chip 10 is more firmly fixed to the support 40. This is preferable. In the present embodiment, an epoxy adhesive is applied as the filler 44.

  The injection position of the filler 44 into the gap 42 may be a position that suppresses at least the intrusion of the mold material 50 during integral molding (described later) with the mold material 50. The molding material 50 protects the circuit portion formed on the circuit chip 20, the bonding wires 60 and 61, and the connection portions (the flow rate detection chip 10, the circuit chip 20, and the leads) with the bonding wires 60 and 61. Provided. Accordingly, since a predetermined region of the flow rate detection chip 10 including the pad portion 16 is covered with the molding material 50, the gap 42 in the region to be covered and the region to be covered before the integral molding with the molding material 50 are performed. The filler material 44 is injected into the gap 42 in a predetermined range from the boundary of the nozzle and the communication portion (the communication groove portion 43 and the gap 42) is not closed, and the gap 42 is closed so that the molding material 50 does not enter. It is preferable.

  In the present embodiment, as shown in FIG. 1A, the groove portion 41 has a reservoir portion 45 that is enlarged in the plane direction from the region covered with the molding material 50 to the region not covered with the molding material 50. By injecting the filler 44 into the portion 45, the mold material 50 is prevented from entering the gap 42 during integral molding. As described above, when the reservoir portion 45 of the filler 44 is formed in a part of the groove portion 41, even if the filler 44 has good fluidity (low viscosity) at the time of injection, a predetermined position ( That is, the filler 44 can be retained in the reservoir 45). In FIG. 1A, the filling material 44 is stored in the planar direction, but the filling material 44 may be stored in the depth direction without changing the width of the gap 42.

  The molding material 50 is made of an electrically insulating material that can be integrally molded, such as an epoxy resin. The flow rate detection chip 10 is disposed in the groove 41 of the support 40, and the cavity portion 11 communicates with the outside on the flow rate detection chip 11. The circuit chip 20 in which the circuit portion is formed, the bonding wires 60 and 61, and the respective portions in the state where the filler 44 is injected into a predetermined range of the gap 42 between the flow rate detection chip 10 and the groove portion 41. Connection portions (flow detection chip 10, circuit chip 20, and lead portions) with bonding wires 60 and 61 are integrally covered.

  Next, an example of a method for manufacturing the thermal flow sensor 100 having the above-described configuration will be described with reference to FIGS. 3A and 3B are cross-sectional views showing the manufacturing method of the thermal flow sensor 100, wherein FIG. 3A is an electrical connection process, FIG. 3B is a filler injection process, and FIG. 3C is a molding process. is there. In addition, the groove part 41 and the communication groove part 43 are previously formed in the support body 40 by the etching.

  First, as shown to Fig.3 (a), the flow volume detection chip | tip 10 is positioned with respect to the groove part 41 of the support body 40, for example, is fixed by sticking. At this time, the flow rate detection part forming surface of the flow rate detection chip 10 and the surface of the support 40 are substantially flush with each other, and a predetermined gap 42 is formed between the flow rate detection chip 10 and the side surface of the groove part 41. Moreover, the circuit chip 20 which has a circuit part is positioned in the edge part of the support body 40, for example, it sticks and fixes. The flow rate detection unit and the circuit unit are electrically connected by the bonding wire 60, and the circuit unit and the lead 30 are electrically connected by the bonding wire 61.

  Next, in the molding process described later, the communication portion (the communication groove portion 43 and the gap 42) is not blocked within a predetermined range from the boundary between the gap 42 in the region covered with the molding material 50 and the region to be covered. The filler 44 is injected into the gap 42 in the range and cured, and the gap 42 is closed so that the molding material 50 does not enter in the molding process described later.

  After the predetermined range of the gap 42 is closed with the filler 44, as shown in FIG. 3C, the circuit chip 20, the bonding wires 60 and 61, and the connection parts (flow rate detection chip 10) with the bonding wires 60 and 61. , Each part of the circuit chip 20 and the lead) are integrally formed using a predetermined mold so that they are integrally covered with the molding material 50. As described above, the thermal flow sensor 100 of the present embodiment that can reduce noise due to turbulent flow and reduce measurement errors due to temperature changes is formed.

  The support 40 and the lead 30 are made of the same constituent material, and are integrated by an outer frame (not shown) in the above process, and the outer frame portion is cut away after forming to form the thermal flow sensor 100.

  Further, the filling material 44 may be injected into the gap 42 in a state where the flow rate detection chip 10 is fixed to the groove portion 41 of the support 40. That is, the filling material 44 may be injected before the electrical connection by the bonding wires 60 and 61 is performed.

(Second Embodiment)
Next, a second embodiment of the present invention will be described based on FIGS. 4 (a) and 4 (b) and FIGS. 5 (a) to 5 (c). 4A and 4B are diagrams illustrating a schematic configuration of the thermal flow sensor 100 according to the present embodiment, in which FIG. 4A is a plan view and FIG. 4B is a cross-sectional view taken along the line BB in FIG. FIGS. 5A and 5B are cross-sectional views showing the manufacturing method of the thermal flow sensor 100 shown in the present embodiment, wherein FIG. 5A shows a filler injection process, FIG. 5B shows a molding process, and FIG. 5C shows a groove forming process. FIG.

  Since the thermal flow sensor 100 and the manufacturing method thereof according to the second embodiment are often in common with those according to the first embodiment, a detailed description of the common parts will be omitted below, and different parts will be mainly described. To do.

  The second embodiment is different from the first embodiment in that the support body 40 has a first support body having a through hole in which the flow rate detection chip 10 can be arranged, a communication portion, and the first support body. It is a point comprised by the 2nd support body which mounts a body.

  In the thermal flow sensor 100 according to the present embodiment, as shown in FIGS. 4A and 4B, the support body 40 on which at least the flow rate detection chip 10 is mounted includes the first support body 40a and the second support body 40a. It is comprised by the support body 40b.

  The first support 40a is made of, for example, the same material as that of the lead 30, and a through hole 46 in which the flow rate detection chip 10 can be arranged is formed instead of the groove 41 in the first embodiment. In the present embodiment, the thickness of the first support 40 a is substantially the same as that of the flow rate detection chip 10, and the dimension of the through hole 46 is set to be substantially the same as the outer shape of the flow rate detection chip 10.

  The second support 40b is made of, for example, a resin material such as polyphenylene sulfide (PPS), and a communication portion is formed. The groove portion 41 shown in the first embodiment is constituted by the surface facing the first support 40a and the through hole 46 formed in the first support 40a in a state where the first support 40a is mounted. Is done. In the present embodiment, a communication groove 48 that communicates with a gap 47 between the outer surface of the first support 40a and the side surface of the second support 40b that faces the outer surface is formed as the communication portion. ing. That is, the communication groove portion 48 and the gap 47 constitute a communication portion. If comprised in this way, the structure of a communication part can be simplified.

  Further, like the groove portion 41, the through hole 46 is formed with a predetermined clearance with respect to the outer shape of the flow rate detection chip 10. Accordingly, a predetermined gap 42 is generated between the side surface of the through hole 46 and the side surface of the flow rate detection chip 10 in a state where the flow rate detection chip 10 is disposed in the through hole 46. Therefore, also in the present embodiment, as in the first embodiment, at the time of integral molding with the molding material 50 (described later), at least intrusion of the molding material 50 into the gap 42 is prevented and the communication portion is not blocked. Filler 44 is injected to close gap 42.

  In the present embodiment, the communication portion formed in the second support body 40b is configured as a communication groove portion 48, and the gap 42 between the side surface of the through hole 46 and the side surface of the flow rate detection chip 10 is formed. In contrast, a part of the structure is communicated. Therefore, since it is necessary to inject the filler 44 into the gap 42 before mounting the first support 40a on the second support 40b, in order to fix the flow rate detection chip 10 in the through hole 46, An adhesive as a filler 44 is injected over the entire side surface of the flow rate detection chip 10. As described above, when the adhesive as the filler 44 is injected over the entire circumference of the side surface of the flow rate detection chip 10, the connection strength of the flow rate detection chip 10 to the through hole 46 can be improved.

  As described above, also in the thermal flow sensor 100 shown in the present embodiment, the cavity 11 of the flow rate detection chip 10 is not directly exposed to the air that is the fluid to be measured. Compared with a configuration in which (40b) is not arranged, noise due to turbulent flow can be reduced. Further, the cavity 11 of the flow rate detection chip 10 is not completely closed by the support body 40 (40a, 40b), and the communication portion formed in the second support body 40b allows the outside of the flow rate detection chip 10 to be connected to the outside. It is in a state of communication. Therefore, the temperature of the fluid in the cavity 11 can change following the temperature change around the thermal flow sensor 100, so that a measurement error due to the temperature change can be reduced.

  Further, in a state where the flow rate detection chip 10 is disposed in the through portion 46, the flow rate detection portion forming surface of the flow rate detection chip 10 and the surface of the first support 40 a are substantially flush with the side surface of the through hole 46. In the gap 42 between the flow rate detection chip 10 and the side surface of the flow rate detection chip 10, an adhesive as a filler 44 that suppresses the intrusion of the molding material 50 into the gap 42 during molding is injected, and at least a part of the gap 42 is blocked. ing. As a result, the cavity 11 is not completely closed by the support 40 (40a, 40b) and communicates with the outside on the flow rate detection chip 10 through the communication part. The mold material 50 is intruded until the cavity 11 is blocked.

  The thermal flow sensor 100 having the above-described configuration can be formed by, for example, the following method. Note that a through hole 46 having substantially the same dimensions as the outer shape of the flow rate detection chip 10 is formed in the first support 40a in advance.

  First, as shown in FIG. 5A, a first support 40a and a lead 30 integrated by an outer frame not shown are arranged on a base 200, and are inserted into a through hole 46 of the first support 40a. A flow rate detection chip 10 is arranged. In this arrangement state, the flow rate detection portion forming surface of the flow rate detection chip 10 and the surface of the first support 40a are substantially flush with each other. In addition, an adhesive as a filler 44 is injected into the gap 42 between the side surface of the through hole 46 whose one surface is blocked by the surface of the base 200 and the side surface of the flow rate detection chip 10 and is cured. As a result, the flow rate detection chip 10 is fixed to the first support body 40, and the gap 42 is closed so that the molding material 50 does not enter in the molding process described later. The flow rate detection unit and the circuit unit are electrically connected by the bonding wire 60, and the circuit unit and the lead 30 are electrically connected by the bonding wire 61.

  Next, as shown in FIG. 5B, the circuit chip 20, the bonding wires 60 and 61, and the connection parts to the bonding wires 60 and 61 (the flow rate detection chip 10, the circuit chip 20, and the lead parts ) Is integrally molded using a predetermined mold so that the mold material 50 is integrally covered with the molding material 50.

  Finally, the first support 40a is fixed to a predetermined position of the second support 40b with, for example, an adhesive. Thereby, the groove part 41 shown by 1st Embodiment is comprised by the through-hole 46 of the 1st support body 40a, and the surface of the 2nd support body 40b. The cavity 11 of the flow rate detection chip 10 is formed between the communication groove 48 formed in the second support body 40b, the outer surface of the first support body 40a, and the side surface of the second support body 40b. The communication part constituted by the gap 47 communicates with the outside on the flow rate detection chip 10. In addition, after the molding process or the groove forming process, the outer peripheral frame portion is cut out to form the thermal flow sensor 100.

  In the present embodiment, in order to fix the flow rate detection chip 10 in the through hole 46, an example in which an adhesive as the filler 44 is injected over the entire side surface of the flow rate detection chip 10 is shown. An injected configuration may be used.

  As described above, the thermal flow sensor 100 of the present embodiment that can reduce noise due to turbulent flow and reduce measurement errors due to temperature changes is formed.

  Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and can be implemented with various modifications.

  In the present embodiment, an example is shown in which the substrate constituting the flow rate detection chip 10 is a semiconductor substrate made of silicon. When the semiconductor substrate is used in this way, the cavity 11 and the thin portion 12 can be easily formed on the substrate by a general semiconductor manufacturing technique. That is, the thermal flow sensor 100 can be manufactured at low cost. However, the substrate may be composed of a glass substrate or the like.

  Moreover, in this embodiment, the support body 40 showed the example comprised by processing one member or two members (1st support body 40a, 2nd support body 40b). However, the configuration of the support 40 is not limited to the above example.

  In the present embodiment, the circuit chip 20 is also disposed on the same support body 40 as the flow rate detection chip 10. However, the circuit chip 20 may be arranged on a member different from the flow rate detection chip 10. In this case, it is preferable that the lead 30 is made of the same material and integrated by the outer peripheral frame.

It is a figure which shows schematic structure of the thermal type flow sensor in the 1st Embodiment of this invention, (a) is a top view, (b) is sectional drawing in the AA cross section of (a). It is a top view which shows the structure of a flow volume detection chip | tip. It is sectional drawing according to process which shows the manufacturing method of the thermal type flow sensor in 1st Embodiment, (a) is an electrical connection process, (b) is a filler injection | pouring process, (c) is a figure which shows a shaping | molding process. It is. It is a figure which shows schematic structure of the thermal type flow sensor in 2nd Embodiment, (a) is a top view, (b) is sectional drawing in the BB cross section of (a). It is sectional drawing according to process which shows the manufacturing method of the thermal type flow sensor shown in 2nd Embodiment, (a) is a filler injection | pouring process, (b) is a formation process, (c) is a figure which shows a groove part formation process. is there.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Flow rate detection chip 11 ... Cavity part 12 ... Thin part 13 ... Heater 20 ... Circuit chip 30 ... Lead 40 ... Support body 41 ... Groove part 42 ... Gap 43 ... Communication groove 44 ... Filler 45 ... Reservoir 50 ... Mold material 60, 61 ... Bonding wire (connection wire)
100 ... Thermal flow sensor

Claims (11)

A flow rate detection chip in which a flow rate detection unit including a heater formed in the thin part is formed on a substrate having a thin part;
A circuit chip electrically connected to the flow rate detection unit via a first connection wire and having a circuit unit for controlling input / output of the flow rate detection unit;
A lead electrically connected to the circuit portion via a second connection wire;
A support body on which at least the flow rate detection chip is mounted;
In a state where the flow rate detection chip is mounted on the support, the first connection wire, the flow rate detection unit, and the flow rate detection unit including the heater are partially exposed to the fluid to be measured. A thermal flow sensor in which each connection part with the circuit part, each connection part between the second connection wire and the circuit part and the lead, and a range including the circuit chip are integrally covered with a molding material. Because
The support body includes a groove portion in which the flow rate detection chip is disposed, and a communication portion that communicates a hollow portion below the thin portion of the substrate with the outside on the flow rate detection chip in a state in which the flow rate detection chip is disposed. And
In a state where the flow rate detection chip is disposed in the groove portion, the flow rate detection portion forming surface and the support surface of the flow rate detection tip are substantially flush with the gap between the groove side surface and the flow rate detection tip side surface. An at least part of the gap is closed by injecting an adhesive at a position that suppresses the mold material from entering the gap at least during molding. The support is, thermal flow sensor according to claim 1, characterized that you have been configured by the same material as lead. Wherein the support, as the communication unit, the thermal flow sensor according to claim 1 or claim 2, characterized in that communicating groove that communicates with the gap is formed. The thermal flow sensor according to claim 3 , wherein the communication groove portion communicates with the gap between at least one side surface of the flow rate detection chip and the groove portion side surface facing the side surface. The thermal flow sensor according to any one of claims 1 to 4 , wherein the adhesive has a reservoir of the adhesive formed in a part of the groove . The support is constituted by a first support having a through-hole in which the flow rate detection chip can be arranged, and a second support having the communication portion and mounting the first support. The thermal type flow sensor according to claim 1 or 2 , characterized by things. The second support body has a communication groove portion that communicates with a gap between the outer surface of the first support member and the side surface of the second support member facing the outer surface as the communication portion. The thermal flow sensor according to claim 6 , wherein the thermal flow sensor is formed. The thermal flow sensor according to any one of claims 1 to 7, wherein the substrate is characterized by a semiconductor substrate der Rukoto. A flow rate detection chip in which a flow rate detection unit including a heater formed in the thin part is formed on a substrate having a thin part;
A circuit chip electrically connected to the flow rate detection unit via a first connection wire and having a circuit unit for controlling input / output of the flow rate detection unit;
A lead electrically connected to the circuit portion via a second connection wire;
Having at least a support on which the flow rate detection chip is mounted;
In a state where the flow rate detection chip is mounted on the support, the first connection wire, the flow rate detection unit, and the flow rate detection unit including the heater are partially exposed to the fluid to be measured. Thermal flow rate sensor formed by integrally covering each connection part with the circuit part, each connection part between the second connection wire and the circuit part and the lead, and a range including the circuit chip with a molding material. A manufacturing method of
The support body includes a groove portion in which the flow rate detection chip is disposed, and a communication portion that communicates a hollow portion below the thin portion of the substrate with the outside on the flow rate detection chip in a state in which the flow rate detection chip is disposed. And
In the state where the flow rate detection chip is arranged in the groove so that the flow rate detection part forming surface of the flow rate detection chip and the support surface are substantially flush with each other, in the gap between the groove side surface and the flow rate detection chip side surface A method of manufacturing a thermal flow sensor , comprising injecting an adhesive and closing at least a part of the gap so that the mold material does not enter the gap during integral molding with the mold material . The support body includes a first support body having a through hole in which the flow rate detection chip can be arranged on a second support body having the communication portion, whereby the through hole and the second support body are mounted. The method of manufacturing a thermal flow sensor according to claim 9 , wherein the groove is formed with a body surface . Wherein after the first of the flow rate detection chip into the through hole of the support body is fixed, according to claim 10, characterized that you mounting the said first support to said second support on Manufacturing method of thermal flow sensor.

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